Flu shot linked to lower risk of heart attack
Threat cut by third, study says
A simple, once-a-year injection - the annual flu shot - may cut the risk of heart attack or dying from a heart-related cause by a third, Canadian-led research suggests.
An international team led by scientists from Toronto’s Women’s College Hospital, who reviewed studies published as far back as 1946, found flu shots are associated with a 36-per-cent lower risk of major cardiac events in the year following vaccination. Such events include death from heart disease or hospitalization for heart attack, unstable angina, stroke, heart failure or an urgent angioplasty - a procedure to restore normal blood flow to the heart.
The benefit was even more pronounced for the highestrisk patients. The findings don’t prove cause and effect, only an association. However, coming at the start of influenza season, the study may help win over skeptics of the flu shot and boost notoriously low vaccination rates, said cardiologist and lead author Dr. Jacob Udell.
"There is really very little risk, and a lot of reward for getting the flu shot," he said.
It’s not clear how flu shots might protect the heart. One leading theory is that flu infections launch an inflammatory response throughout the body that may dislodge plaque deposits that have otherwise been stable for decades but that suddenly burst, squeezing off blood supply to the heart.
Recent studies have shown that people have a higher risk of heart attack, congestive heart failure or stroke in the first days or week after coming down with flu.
Udell’s team reviewed six “top line” randomized clinical trials - five published, one unpublished - involving 6,735 patients.
One-third had heart disease. The mean age was 67; half were women. Participants received either a flu vaccine, a placebo vaccine or no injection.
Among the patients treated with flu vaccine, 2.9 per cent developed a major cardiovascular event within one year of followup, compared with 4.7 per cent treated with placebo.
The full study appears in this week’s issue of the Journal of the American Medical Association.
A new flu vaccine is formulated each year to protect against the flu strains expected to circulate that season. An annual flu shot is about 60-percent effective in provoking enough of an immune response to protect against the flu.
"Until we have one of those vaccines that will protect us regardless of what flu season it is, the best thing we have at our disposal … is better than nothing," Udell said.
(From The Vancouver Sun)